Synchronous application technology defines synchronous playback of a plurality of digital streams stored on different recording media, so that it appears to users to be playback of a single movie.
Synchronous applications are composed of different types of digital streams including main streams and substreams. A main stream is a digital stream containing high-quality video, whereas a substream is a digital stream without such high-quality video. Main streams are distributed to users via large-volume optical discs typified by BD-ROMs storing the main streams. On the other hand, substreams are distributed to users via, for example, the Internet.
Since digital streams constituting a single movie can be distributed to users via different media, more flexibility is offered in production of variations of the movie. Thus, wider variations can be provided to playback of a single movie.
Note that the following patent literature discloses prior art relating to synchronous application technology. Patent Literature 1:
JP Patent Application Publication No. 2002-247526